Enable flake8-errmsg linting rules (#267)

See https://docs.astral.sh/ruff/rules/#flake8-errmsg-em.

.ruff.toml

@@ -9,6 +9,7 @@ select = [
   "COM", # flake8-commas
   "DTZ", # flake8-commas
   "E", # pycodestyle errors
+  "EM", # pycodestyle errors
   "F", # pyflakes errors
   "I", # isort
   "ISC", # flake8-implicit-str-concat

src/common/dates.py

@@ -50,7 +50,8 @@ def parse_datetime(text: str, formats: list[str] = frozenset([
         except ValueError:
             pass
 
-    raise ValueError(f"'{text}' could not be parsed as a date with any of the formats: {str(formats)}")
+    msg = f"'{text}' could not be parsed as a date with any of the formats: {str(formats)}"
+    raise ValueError(msg)
 
 
 def date(year: int, month: int, day: int) -> datetime:

src/common/endoflife.py

@@ -114,7 +114,8 @@ class Product:
 
     def replace_version(self, version: str, date: datetime) -> None:
         if version not in self.versions:
-            raise ValueError(f"version {version} cannot be replaced as it does not exist for {self.name}")
+            msg = f"version {version} cannot be replaced as it does not exist for {self.name}"
+            raise ValueError(msg)
 
         logging.info(f"replacing version {version} ({self.versions[version]} -> {date}) in {self.name}")
         self.versions[version] = date

src/common/git.py

@@ -20,7 +20,8 @@ class Git:
             child = run(f"git {cmd}", capture_output=True, timeout=300, check=True, shell=True, cwd=self.repo_dir)
             return child.stdout.decode("utf-8").strip().split("\n")
         except ChildProcessError as ex:
-            raise RuntimeError(f"Failed to run '{cmd}': {ex}") from ex
+            msg = f"Failed to run '{cmd}': {ex}"
+            raise RuntimeError(msg) from ex
 
     def setup(self, bare: bool = False) -> None:
         """Creates the repository path and runs: